fix: remove obsolete test for removed IssueActivity datamodel

Removed test_real_codebase_issueactivity test which was checking for the
existence of the IssueActivity datamodel that was removed during the
cleanup of the old issue management system.

The test was validating:
- Existence of IssueActivity class
- Specific optimization methods (has_implementation_activity, contains_keyword)
- Specific properties (activity_type_value, formatted_date, truncated_details)

Since the entire markitect/issues/ directory was removed in favor of the
issue-facade system, this test is no longer relevant. All other datamodel
optimizer tests continue to pass.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/test_datamodel_optimizer.py

@@ -187,30 +187,6 @@ def test_model_processing():
         assert '"total_datamodels"' in json_report
         assert '"total_opportunities"' in json_report
 
-    def test_real_codebase_issueactivity(self):
-        """Test against real IssueActivity to verify it recognizes our optimizations."""
-        project_root = Path(__file__).parent.parent
-
-        discovery = DatamodelDiscovery(project_root)
-        datamodels = discovery.discover_datamodels()
-
-        # Should find IssueActivity
-        assert "IssueActivity" in datamodels
-
-        model = datamodels["IssueActivity"]
-        assert model.is_dataclass is True
-        assert len(model.properties) >= 5  # Should have the properties we added
-        assert len(model.methods) >= 3     # Should have the methods we added
-
-        # Should have the optimization methods we added
-        assert "to_dict" in model.methods
-        assert "has_implementation_activity" in model.methods
-        assert "contains_keyword" in model.methods
-
-        # Should have the properties we added
-        assert "activity_type_value" in model.properties
-        assert "formatted_date" in model.properties
-        assert "truncated_details" in model.properties
 
     def test_impact_scoring(self, temp_project):
         """Test that impact scoring works correctly."""